QtNetwork.QHostInfo Class Reference

The QHostInfo class provides static functions for host name lookups. More...

Inheritance diagram for QtNetwork.QHostInfo:

Collaboration diagram for QtNetwork.QHostInfo:

Public Types
enum	HostInfoError { HostNotFound = 1, NoError = 0, UnknownError = 2 }
	More...

Public Member Functions
	QHostInfo (QHostInfo d)
	QHostInfo (int lookupId=-1)
virtual void	CreateProxy ()
new void	Dispose ()

Static Public Member Functions
static void	AbortHostLookup (int lookupId)
static QHostInfo	FromName (string name)
static string	LocalDomainName ()
static string	LocalHostName ()
static int	LookupHost (string name, QObject receiver, string member)

Protected Member Functions
	QHostInfo (System.Type dummy)

Protected Attributes
SmokeInvocation	interceptor

Properties
new System.Collections.Generic.List < QHostAddress >	Addresses [get, set]
new QHostInfo.HostInfoError	Error [get, set]
new string	ErrorString [get, set]
new string	HostName [get, set]
new int	LookupId [get, set]
virtual System.IntPtr	SmokeObject [get, set]

Detailed Description

The QHostInfo class provides static functions for host name lookups.

QHostInfo uses the lookup mechanisms provided by the operating system to find the IP address(es) associated with a host name, or the host name associated with an IP address. The class provides two static convenience functions: one that works asynchronously and emits a signal once the host is found, and one that blocks and returns a QHostInfo object.

To look up a host's IP addresses asynchronously, call lookupHost(), which takes the host name or IP address, a receiver object, and a slot signature as arguments and returns an ID. You can abort the lookup by calling abortHostLookup() with the lookup ID.

Example:

// To find the IP address of qt.nokia.com

QHostInfo::lookupHost("qt.nokia.com",

this, SLOT(printResults(QHostInfo)));

// To find the host name for 4.2.2.1

QHostInfo::lookupHost("4.2.2.1",

this, SLOT(printResults(QHostInfo)));

The slot is invoked when the results are ready. The results are stored in a QHostInfo object. Call addresses() to get the list of IP addresses for the host, and hostName() to get the host name that was looked up.

If the lookup failed, error() returns the type of error that occurred. errorString() gives a human-readable description of the lookup error.

If you want a blocking lookup, use the QHostInfo::fromName() function:

QHostInfo info = QHostInfo::fromName("qt.nokia.com");

QHostInfo supports Internationalized Domain Names (IDNs) through the IDNA and Punycode standards.

To retrieve the name of the local host, use the static QHostInfo::localHostName() function.

Note: Since Qt 4.6.1 QHostInfo is using multiple threads for DNS lookup instead of one dedicated DNS thread. This improves performance, but also changes the order of signal emissions when using lookupHost() compared to previous versions of Qt. Note: Since Qt 4.6.3 QHostInfo is using a small internal 60 second DNS cache for performance improvements.

See also QAbstractSocket and RFC 3492.

Member Enumeration Documentation

enum QtNetwork.QHostInfo.HostInfoError

This enum describes the various errors that can occur when trying to resolve a host name.

See also error() and setError().

Enumerator:

HostNotFound	No IP addresses were found for the host.
NoError	The lookup was successful.
UnknownError	An unknown error occurred.

Constructor & Destructor Documentation

QtNetwork.QHostInfo.QHostInfo ( System.Type  dummy )

protected

QtNetwork.QHostInfo.QHostInfo

(

QHostInfo

d

)

Constructs a copy of other.

QtNetwork.QHostInfo.QHostInfo

(

int

lookupId = -1

)

Constructs an empty host info object with lookup ID id.

See also lookupId().

Member Function Documentation

static void QtNetwork.QHostInfo.AbortHostLookup ( int  lookupId )

static

Aborts the host lookup with the ID id, as returned by lookupHost().

See also lookupHost() and lookupId().

virtual void QtNetwork.QHostInfo.CreateProxy ( )

virtual

new void QtNetwork.QHostInfo.Dispose

(

)

static QHostInfo QtNetwork.QHostInfo.FromName ( string  name )

static

Looks up the IP address(es) for the given host name. The function blocks during the lookup which means that execution of the program is suspended until the results of the lookup are ready. Returns the result of the lookup in a QHostInfo object.

If you pass a literal IP address to name instead of a host name, QHostInfo will search for the domain name for the IP (i.e., QHostInfo will perform a reverse lookup). On success, the returned QHostInfo will contain both the resolved domain name and IP addresses for the host name.

See also lookupHost().

static string QtNetwork.QHostInfo.LocalDomainName ( )

static

Returns the DNS domain of this machine.

Note: DNS domains are not related to domain names found in Windows networks.

See also hostName().

static string QtNetwork.QHostInfo.LocalHostName ( )

static

Returns the host name of this machine.

See also hostName().

static int QtNetwork.QHostInfo.LookupHost ( string  name, QObject  receiver, string  member  )

static

Looks up the IP address(es) associated with host name name, and returns an ID for the lookup. When the result of the lookup is ready, the slot or signal member in receiver is called with a QHostInfo argument. The QHostInfo object can then be inspected to get the results of the lookup.

The lookup is performed by a single function call, for example:

QHostInfo::lookupHost("www.kde.org",

this, SLOT(lookedUp(QHostInfo)));

The implementation of the slot prints basic information about the addresses returned by the lookup, or reports an error if it failed:

void MyWidget::lookedUp(const QHostInfo &host)

{

if (host.error() != QHostInfo::NoError) {

qDebug() << "Lookup failed:" << host.errorString();

return;

}

foreach (const QHostAddress &address, host.addresses())

qDebug() << "Found address:" << address.toString();

}

If you pass a literal IP address to name instead of a host name, QHostInfo will search for the domain name for the IP (i.e., QHostInfo will perform a reverse lookup). On success, the resulting QHostInfo will contain both the resolved domain name and IP addresses for the host name. Example:

QHostInfo::lookupHost("4.2.2.1",

this, SLOT(lookedUp(QHostInfo)));

Note: There is no guarantee on the order the signals will be emitted if you start multiple requests with lookupHost().

See also abortHostLookup(), addresses(), error(), and fromName().

Member Data Documentation

SmokeInvocation QtNetwork.QHostInfo.interceptor

protected

Property Documentation

new System.Collections.Generic.List<QHostAddress> QtNetwork.QHostInfo.Addresses

getsetadd

Returns the list of IP addresses associated with hostName(). This list may be empty.

Example:

QHostInfo info;

...

if (!info.addresses().isEmpty()) {

QHostAddress address = info.addresses().first();

// use the first IP address

}

Sets the list of addresses in this QHostInfo to addresses.

new QHostInfo.HostInfoError QtNetwork.QHostInfo.Error

getset

Returns the type of error that occurred if the host name lookup failed; otherwise returns NoError.

Sets the error type of this QHostInfo to error.

new string QtNetwork.QHostInfo.ErrorString

getset

If the lookup failed, this function returns a human readable description of the error; otherwise "Unknown error" is returned.

Sets the human readable description of the error that occurred to str if the lookup failed.

new string QtNetwork.QHostInfo.HostName

getset

Returns the name of the host whose IP addresses were looked up.

Sets the host name of this QHostInfo to hostName.

new int QtNetwork.QHostInfo.LookupId

getset

Returns the ID of this lookup.

Sets the ID of this lookup to id.

virtual System.IntPtr QtNetwork.QHostInfo.SmokeObject

getset